Please tell me I'm not the only new mom freaked out a little by the anterior fontanelle?

DD is almost 4 weeks old and I never really paid much attention to it until yesterday. DH was "styling" her hair and noticed that her fontanelle was pretty indented, which totally freaked him out, which in turn made me question it a little. She was sitting upright against his legs, and when we changed her position it filled in and went back to normal. From what I could find on the internet, this is normal. She is not sick and shows no signs of dehydration, eats like a champ (EBF), has plenty of wet/good quality soiled diapers daily and is gaining weight steadily (where did my tiny boo go so fast?). Of course, it does rattle my breastfeeding confidence and makes me wonder if she is slighly dehydrated. But had DH not noticed it, I would never have questioned anything. She seems totally happy and thriving.

Her 1 month check-up is next Monday so I will ask the ped then - just looking for other moms experiences.

My daughter's was often visible and sorta indented, and my son's never was, so I'd consider it a feature of what her body normally looks like, and you can use that as comparison to what's normal for her as time goes on.